The Internet Watch Foundation reports that the number of websites showing and selling images of child abuse has fallen by 10% in the last 12 months.

“These websites, although reducing in number, represent an extremely serious problem,” said Peter Robbins, chief executive of the IWF.

Of the 1,536 unique domains known to the IWF as hosting images of child abuse, 74% were run for profit. The remaining sites were places abusers shared or swapped images.

In its report, the IWF said: “1,536 domains represent a problem of a scale which can be seriously targeted and significantly disrupted through international efforts.” It said that about 69% of the children depicted in the images it saw were between zero and 10. About 24% involved children aged six or under. About 58% of the images seen showed the most serious sorts of abuse – involving rape or torture.

The IWF has said it and its international partners would target these key domain sellers in the next year to get abuse sites delisted and removed from the net.

The report also noted the increasing sophistication of the methods used by site owners to escape detection and avoid being shut down. Many sites scramble domain names, hide payment systems and split images across sub-domains or remote servers to evade law enforcement agencies.